     (-index [coll]))
 
 (defprotocol IIndexed
-  (-nth [coll n])
-  (-nth [coll n not-found]))
+  (-nth [coll n] [coll n not-found]) )
 
 (defprotocol ISeq
   (-first [coll])
   (-rest [coll]))
 
 (defprotocol ILookup
-  (-lookup [o k])
-  (-lookup [o k not-found]))
+  (-lookup [o k] [o k not-found]))
 
 (defprotocol IAssociative
   #_(-contains-key? [coll k])

  (-with-meta [o meta]))

(defprotocol IReduce
  (-reduce [coll f])
  (-reduce [coll f start]))

(defprotocol IEquiv
  (-equiv [o other]))

(defn disj
  [coll v]
  (when coll (-disjoin coll v)))

